Resumen
The rapid growth of socioeconomic activity The rapid growth of socioeconomic activity in Addis Ababa city creates huge demand for delivery of goods involving urban freight transport. The rise in demand combined to the limited space of the city increases the manoeuvring difficulty of freight vehicles. These factors highly contribute to traffic congestion, traffic accident and environmental degradation. The road transport is serving as the major transport means of the country and Addis Ababa city has the largest share of vehicular fleet. The objective of the study was to identify the existing constraints of traffic congestion and exhaust emission from freight vehicles inside the city and map out the benefits of night delivery system. The study used classified vehicle count based in their loading capacity, travel time and travel length between the origin (freight gates) and the destination points in the city center, and direct tail pipe emission measurement of CO and CO2 gases from freight vehicles based on their age group as main input. The collected data's are analyzed by taking two different scenarios of the current condition and the other by shifting the freight vehicles movement to the night time. The result showed total estimated vehicle-kilometer of 183,873.11 and vehicle-hour of 6,784.96 releasing 36.84 tons of CO2 and 100 kilogram of CO pollutant gases at each day. Whereas the night delivery reduces the travel time by 30 ? 40%, vehicle - kilometer by 6% and vehicle-hour by 33.49% for every delivery operation saving the total emission of CO2 by 10.46% and CO by 10.80% every single day. It can be deducted that night delivery could be one of the solution to the current freight transport problem of Addis Ababa city.